Components that are designed to hold their relative position until a specific subterranean location is reached at which time they are actuated to move relatively to operate various tools. Typically these parts are held together with shear pins. When the time comes for the tool actuation various techniques are used to break the shear pin and get the parts moving. There can be a ball seat that gets a ball followed by pressuring up to move one sleeve with respect to another where the shear pin extends in both sleeves. The result is that the shear pin shears and the parts move and the tool is actuated. It can be done by setting down weight or by picking up and setting down in a pattern in combination with a j-slot where after so many cycles there is a longer motion possible and the shear pin is sheared.
Shear pins can be a source of problems as they sometimes break at less than or greater than the force for which they are designed. Sometimes they shear in a way that a remnant of the shear pin gets jammed in between the relatively moving parts. When running a string into a wellbore there is frequently impacts on the wellbore wall and some of those can be hard enough to break a shear pin and get components moving at an inopportune time. This can have the result of setting a subterranean device/tool in an undesired location or in other cases require string removal to redress parts and to reset them to their original position for another try. Having to do this even once can be prohibitively expensive so that such occasions are to be avoided at all costs.
One solution to this problem that was tried in the past was to use a locking dog to prevent loads from reaching a shear pin until the dog was undermined such as with a ball landing on a sleeve that shifts with pressure to undermine the dog so that a force can reach the shear pin. This is illustrated in U.S. Pat. No. 7,503,390. Another approach is to use a locking collet that moves radially to release components for relative movement when urged by applied pressure as shown in U.S. Pat. No. 7,426,964. Other references that deal more generally with shear pin applications are U.S. Pat. Nos. 5,826,652 and 5,462,121.
The present invention in one embodiment replaces the shear pin or pins with one or more collets that are held captive in a groove by a pressure balanced piston that is insensitive to changes in tubing or annulus pressure. At a selected time, spaced apart ports that lead to opposed ends of the floating piston are isolated from each other so that pressure can build on one of the ports to move the sleeve preferably in the downhole direction to release the collet. The same pressure that releases the collet can move a sleeve in the opposite direction than the movement of the floating piston to actuate any number of different tools. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the detailed description of the preferred embodiment and the associated drawings while recognizing that the claims state the full scope of the invention.